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mysqlinnodb

cannot add foreign key/cascade delete to table (no error)


i have table called resume

here is that table export :

CREATE TABLE `resumes` (
  `id` int(10) UNSIGNED NOT NULL,
  `title` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
  `province_id` int(10) UNSIGNED NOT NULL,
  `city_id` int(10) UNSIGNED NOT NULL,
  `name` char(100) COLLATE utf8_unicode_ci NOT NULL,
  `last_name` char(100) COLLATE utf8_unicode_ci NOT NULL,
  `email` char(50) COLLATE utf8_unicode_ci NOT NULL,
  `mobile` char(255) COLLATE utf8_unicode_ci NOT NULL,
  `phone` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
  `address` char(200) COLLATE utf8_unicode_ci NOT NULL,
  `confirm` tinyint(1) NOT NULL DEFAULT '0',
  `image` varchar(100) COLLATE utf8_unicode_ci DEFAULT NULL,
  `created_at` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
  `deleted_at` timestamp NULL DEFAULT NULL,
  `gender` tinyint(1) NOT NULL DEFAULT '0',
  `bdate` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL,
  `marrieg` tinyint(1) NOT NULL DEFAULT '0',
  `military_service` tinyint(1) NOT NULL DEFAULT '0',
  `text` text COLLATE utf8_unicode_ci,
  `password` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
  `token` varchar(100) COLLATE utf8_unicode_ci NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Indexes for dumped tables
--

--
-- Indexes for table `resumes`
--
ALTER TABLE `resumes`
  ADD PRIMARY KEY (`id`),
  ADD UNIQUE KEY `email` (`email`),
  ADD UNIQUE KEY `mobile` (`mobile`);

--
-- AUTO_INCREMENT for dumped tables
--

--
-- AUTO_INCREMENT for table `resumes`
--
ALTER TABLE `resumes`
  MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT;

i have another table called `resume_researches i want to add forign key constraint and cascade delete to this table (referencing resumes table ) i run this code

    ALTER TABLE resume_researches
   ADD CONSTRAINT `fk_resumes_resume_researches`
   FOREIGN KEY (`resume_id` )
   REFERENCES `resumes` (`id` )
   ON DELETE CASCADE ;  

here is the output

 MySQL returned an empty result set (i.e. zero rows). (Query took 0.0150 seconds.)
ALTER TABLE resume_researches ADD CONSTRAINT `fk_resumes_resume_researches` FOREIGN KEY (`resume_id` ) REFERENCES `resumes` (`id` ) ON DELETE CASCADE

but in phpmyadmin there is no relation view and when i export this table here is the result

CREATE TABLE `resume_researches` (
  `id` int(11) NOT NULL,
  `resume_id` int(11) UNSIGNED NOT NULL,
  `title` varchar(100) COLLATE utf8_persian_ci NOT NULL,
  `text` text COLLATE utf8_persian_ci NOT NULL,
  `date` varchar(50) COLLATE utf8_persian_ci NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_persian_ci;

--
-- Indexes for dumped tables
--

--
-- Indexes for table `resume_researches`
--
ALTER TABLE `resume_researches`
  ADD PRIMARY KEY (`id`),
  ADD KEY `fk_resumes_resume_researches` (`resume_id`);

--
-- AUTO_INCREMENT for dumped tables
--

--
-- AUTO_INCREMENT for table `resume_researches`
--
ALTER TABLE `resume_researches`
  MODIFY `id` int(11) NOT NULL AUTO_INCREMENT;

whats wrong ? why there is no reference to the resumes table in the structure ?


Solution

  • FOREIGN KEYs do not work with MyISAM; use InnoDB instead.

    Don't use CHAR for variable length columns; use VARCHAR.

    Don't mix collations (utf8_unicode_ci vs utf8_persian_ci). (There are cases where it is ok, but probably not here.)